1. Field of the Invention
This invention relates generally to devices for feeding bar stock to processing equipment, and more particularly to a feeder for bar stock to a turning machine such as an automatic lathe, for example.
2. Description of the Prior Art
It is important that the centerline of bar stock fed to a turning machine such as an automatic lathe, for example, be aligned with the centerline of the lathe spindle. Since the stock spins while being processed, it is important to limit radial free play of the stock, to avoid whipping, vibration and other undesirable action of the stock in the feeder. It is also desirable to be able to accommodate quick changes of bar cross sectional size, while maintaining alignment of the stock centerline with the spindle centerline.
In some conventional designs of bar stock feeders, the bar is supported in a tube which must be swung out from operating position in order to load the bar stock from the front end. This requires significant floor space. Also, the impact of returning the tube to its operating position can cause the alignment with the turning machine to be adversely affected. U.S. Pat. No. 4,953,429 to Arisaka et al. for Apparatus for Rotatably Supporting and Feeding Elongated Rod Member schematically shows some such prior art arrangements in FIGS. 10 (a) and 10 (b).
As stated in its abstract, the U.S. Pat. No. 4,289,051 to Ramunas for an Object Centering and Moving Mechanism describes a mechanism to raise a round or hexagonal object to establish its center on a fixed reference line, regardless of the object's diameter. First and second calipers engage opposite sides of each object which senses its diameter. Simultaneously, the calipers act through a lever with a two-to-one mechanical advantage so that a stop on the linkage coacts with a fixed frame. The calipered diameter of the object determines the positioning of the stop relative to the frame so that the center of the object is on a fixed reference line regardless of the object's diameter.
The Goda U.S. Pat. No. 4,961,358 for Apparatus for Feeding Elongated Material describes an apparatus which includes plurality of longitudinally spaced support members 6. Each of the support members includes a workpiece contact and guide ring 8, and each guide ring is pivotable on a horizontal axis perpendicular to the length of the material being fed. In this manner, the support members can be pivoted to accommodate and center workpieces of differing diameters (see particularly FIG. 9 which shows material 31 being fed through a support member contact ring 8).
The Peris U.S. Pat. No. 4,413,939 for a Bar Stock Feeder describes a bar stock feeding apparatus having both horizontal and vertical adjustment. Vertical adjustment is accomplished by turning threaded vertical adjusting posts (20 and 30 in FIG. 1) on the rear and front of the carrier assemblies.
The Brochard et al. U.S. Pat. No. 3,677,114 for Positioning The Work in a Milling Lathe describes a milling lathe which has driving rollers (4) connected to vertically movable cross pieces (6) in which are mounted nuts (7a and 7b). A vertical screw (8) with two threads (8a and 8b) having opposite pitch extends through the nuts of the cross pieces. Thus, turning the screw (8) causes movement of the cross pieces and thus the rollers toward or away from the axis of the bar in a symmetrical manner.
Additional patents of general interest are U.S. Pat. No. 3,527,126 to Jones, Jr. for Stock Feeding Apparatus with Chain Device; U.S. Pat. No. 4,875,396 to Gathings for Apparatus for Feeding Bar Stock to a Machining Operation; U.S. Pat. No. 3,696,696 to Bechler for Bar Feed for Automatic Lathe; and U.S. Pat. No. 4,068,546 to Werkmeister for Feed Apparatus for Screw Machine. Among the aforementioned patents. the Arisaka et al. patent also shows oil supplying means and damper means spaced along the stock.
There has remained a need for a feeder which is open at the top to receive bar stock, which adequately supports and centers virtually the entire length of the bar stock being fed to the turning machine and which can be readily adjusted to accommodate different cross-sectional dimensions of bar stock.